1. Field Of The Invention
In a typical immunochemical assay, a solid phase (plastic bead or the like) coated with an immunoreactant such as an antibody or antigen is added to a sample possibly containing the complimentary antibody or antigen to be assayed. If present, the immunoreactant in the sample will react with the affixed immunoreactant and thereby adhere to the solid support. A reagent containing a known quantity of one of the immunoreactants which has been labeled with a detectable member such as an enzyme, radioisotope or fluorescent moiety can then be added to react with one of the immunoreactants on the solid support. The solid support can then be separated from the reaction medium and examined to determine the presence or absence of labeled reagent.
The simple separation of the solid phase from the reaction medium can be accomplished in a number of ways. One method involves aspirating the liquid phase from the reaction vessel, another involves carefully decanting the liquid and still another involves using a reaction container with a crimped or constricted orifice to retain the solid phase while allowing the liquid phase to be poured off.
Each of the foregoing methods of decantation involves handling the reaction containers or test tubes individually, and at the very least, the established procedures are time consuming.
The present invention has solved the problems involved in performing a routine task on a large number of samples. More particularly, the claimed apparatus simplifies and expedites the performance of immunochemical determinations by facilitating the separation of a solid phase or precipitate from a liquid phase.
Using the claimed apparatus, the reaction vials or test tubes are vertically aligned in the test-tube holder in the conventional manner. Thus arrayed, tops of the tubes are covered with a retaining means having a perimeter which engages with the sides of the test tube rack. The entire apparatus is inverted and the liquid contents are removed from the tubes and the solid phase is retained. The apparatus is returned to the up-right position and the solid phase may then be examined for the presence of the labeled reagent.
It should be apparent that this apparatus permits the decantation of an entire rack of tubes simultaneously. Furthermore, note that the liquid phase can be uniformly removed. This cannot be assured where each tube is individually aspirated. The chances of misplacing an individual tube are also eliminated. A misplaced assay means lost time, money and perhaps even erroneous results due to confusion or changes in the immunoreactants which may occur during time spent looking for the tube.
2. Description Of The Prior Art
The results of a recent patentability search disclosed a variety of references describing test tube racks, but none could be found to describe or even suggest the claimed combination.
In particular, U.S. Pat. No. 3,643,812 to Mander, et al discloses a storage rack for test tubes having a cover attachable to the walls of the rack, but it appears to be primarlily for support and not to decant the liquid from the test tube.
U.S. Pat. No. 3,480,152 to Walsh describes a storage rack for vessels which are to be inverted to minimize exposure of the contents to air. The only similarity to the present invention is that the tubes and rack are inverted during the decantation procedure.
U.S. Pat. Nos. 1,188,146 and 4,124,122 both describe test tube racks structurally similar to part of the claimed apparatus, but again, neither describes any structure suitable for selectively decanting the liquid contents of the tubes.